System and method for providing real-time super-resolution for compressed videos

ABSTRACT

A real-time system and method for displaying video on a display are disclosed. Received compressed video data is decoded to produce an uncompressed first video frame, a first frame syntax element, an uncompressed second video frame, and a second frame syntax element. A computationally intensive process is applied to the uncompressed first video frame to produce an enhanced first video frame. A block having a portion of the enhanced first video frame from the enhanced first video frame is adaptively transferred to the uncompressed second video frame to produce an enhanced second video frame without applying the computationally intensive process to the uncompressed second video frame. The transferring is guided by the first frame syntax element and the second frame syntax element. The enhanced first video frame and the enhanced second video frame are displayed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/340,203, filed May 23, 2016, entitled “FAST:Free Adaptive Super-Resolution via Transfer for Compressed Videos,”which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to video processing, and moreparticularly, is related to optimizing video processing by leveragingexisting compression parameters.

BACKGROUND OF THE INVENTION

High resolution displays are garnering increasing popularity.Televisions with 8K resolution (7680×4320 pixels) display are alreadyavailable for sale, and even a cellphone can have 4K Ultra-HD (highdefinition) resolution (3840×1260 pixels). Unfortunately, theavailability of high resolution media content has not kept up with theincrease in display resolutions. For example, one popular videostreaming service currently offers only 26 titles in 4K Ultra-HDresolution. In addition, transmitting 4K Ultra-HD video requires highcommunication bandwidth. Given the abundant amount of existing lowerresolution videos, as well as limited communication bandwidth, it wouldbe desirable to up-sample these videos to higher resolution at thedisplay.

The default up-sampling on televisions is typically simple interpolationand filtering with added sharpening. Due to the simplicity of thesemethods, the visual quality of the output is generally not satisfactory.Super resolution (SR) can provide higher visual quality results byexploiting the non-local similarity of patches or learning a mappingrelating pixels from the low-resolution videos to pixels ofhigh-resolution videos from external datasets. However, SR algorithmsare computationally more expensive and slower than simpleinterpolation/filtering. For instance, state-of-the-art neural networkbased SR algorithms require powerful graphical processing units (GPUs)such as the NVIDIA Grid K2 8GB graphics card that consume around 225W toachieve real-time performance. The speed and power consumption of thesealgorithms, therefore, limit their applicability to televisions andmobile screens.

There are two main forms of super-resolution algorithms: single frameand multiple frame. Typically, televisions use simple single-frame basedup-samplers, including bicubic, sinc, Lanczos, Catmull-Rom, andMitchell-Netravali. These up-samplers are generally based on simplesplines, enabling real-time throughput. However, since these methods arenot content adaptive, they may introduce unwanted video artifacts.

More sophisticated super-resolution algorithms typically leveragemachine learning techniques. Among them are sparse-representation,Kernel Ridge Regression (KRR), anchored neighbor regression (ANR), andin-place example regression. More recently, deep neural networks havebeen used to perform super-resolution (e.g. SRCNN). Such methods applyseveral layers of convolution and non-linear functions to map thelow-resolution image to higher resolution. They achieve state-of-the-artresults, but at high computation cost. As an example, SRCNN use filtersof size 9×9×64, 64×32, 32×5×5, which amounts to 8032 multiplications perpixel. Hence, it is significantly more complicated than simpleinterpolation with one filter.

Even if consumer devices can be accelerated with high powered GPUs(e.g., K2 consumes 225W) to achieve real-time performance, these GPUsconsume far too much power to be embedded in televisions and portabledevices like phones and tablets. Moreover, even with high computationresources, these super-resolution algorithms can only achieve real-timethroughput on high-definition (HD) videos (1920×1080), and not on videosof 4K resolution and beyond. Complementary to learning approaches, thereare algorithms that exploit the self-similarities of blocks within eachimage. However, they are much slower than SRCNN.

Previous multiple-frame based super-resolution algorithms have beenlargely based on the registration of neighboring frames. Many of thesealgorithms are iterative, including the Bayesian based approach and al_(i)-regularized total variation based approach. At the same time,there are non-iterative methods that avoid registration with non-localmean and 3D steer kernel regression. Deep neural networks can also beused in the form of bidirectional recurrent convolutional networks, anddeep draft-ensemble learning. Unfortunately, these multiple-framealgorithms are generally too slow for real-time applications and aregenerally run offline. Other video coding techniques, for example,motion compensation and Group-of-pictures (GOP) structure are similarlyproblematic. Therefore, there is a need in the industry to address oneor more of the abovementioned shortcomings.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a system and method forproviding real-time super-resolution for compressed videos. Brieflydescribed, the present invention is directed to a real-time system andmethod to display video. Received compressed video data is decoded toproduce an uncompressed first video frame, a first frame syntax element,an uncompressed second video frame, and a second frame syntax element. Acomputationally intensive process is applied to the uncompressed firstvideo frame to produce an enhanced first video frame. A block having aportion of the enhanced first video frame from the enhanced first videoframe is adaptively transferred to the uncompressed second video frameto produce an enhanced second video frame without applying thecomputationally intensive process to the uncompressed second videoframe. The transferring is guided by the first frame syntax element andthe second frame syntax element. The enhanced first video frame and theenhanced second video frame are displayed.

Other systems, methods and features of the present invention will be orbecome apparent to one having ordinary skill in the art upon examiningthe following drawings and detailed description. It is intended that allsuch additional systems, methods, and features be included in thisdescription, be within the scope of the present invention and protectedby the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present invention. The drawingsillustrate embodiments of the invention and, together with thedescription, serve to explain the principles of the invention.

FIG. 1 is a block diagram illustrating a first embodiment of a real-timevideo processing system.

FIG. 2 is a flowchart showing the main steps of the first embodiment ofFIG. 1.

FIG. 3 is a series of graphs showing ringing and blurring addressable byusing thresholds with the adaptive transfer process.

FIG. 4 is a flowchart of an exemplary process for applying accumulatederror analysis to the FAST framework of FIG. 2.

FIG. 5 is a schematic diagram illustrating an example of a system forexecuting functionality of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

The embodiments of the present invention disclosed herein share someinsights in common with in-place regression which performs local blockprediction inside the same frame, but the embodiments in additionimportantly employ predictions across frames, which may be of negligiblecost when exploiting embedded information in compressed videos.

The embodiments illustrate examples of one aspect of the presentinvention, called Free Adaptive Super resolution via Transfer (FAST) toaccelerate existing single image based SR algorithms. FAST leverages theinter-frame similarity between adjacent frames in a video sequence. FASTtransfers the SR result from a first frame to a second frame and, insome cases, subsequent frames, such that SR is only directly applied toa subset of frames. The information leveraged for the transfer isalready embedded in the compressed video, and the processing used forthe transfer has a computational cost comparable to bicubicinterpolation. Therefore, the transfer step has negligible run time andcomputation cost compared with the original SR algorithms. As usedwithin this disclosure, the terms “transfer” and “transferring” refer tocopying/replicating of pixels, blocks and/or syntax elements from afirst video frame to a second video frame.

As will be described in detail below, the FAST framework performs thefollowing: transfer of super-resolution pixels using motioncompensation; adaptive transfer for higher visual quality (i.e., PSNR);non-overlapping block structure for reduced computation combined withdeblocking filtering to reduce blocking artifacts; and exploit blockstatistics for reduced computation.

It should be noted that while the embodiments are generally directed toapplication of super resolution to frames using embedded videocompression parameters, the invention is not limited to superresolution. A person having ordinary skill in the art will recognizethat other types of video processing may be used in conjunction with orinstead of super resolution process, including, for example, but notlimited to, de-noising, dynamic range expansion, objectrecognition/detection, optical flow estimation, time-to-contactestimation, tracking in videos, video stabilization, video segmentation,frame interpolation, scene understanding, deblurring, high dynamic rangeenhancement, and visual style editing, among others.

Compressed video formats, for example, bit streams compressed using MPEGor ITUT compression, contain information relating pixels between frames,including, for example, motion vectors, block structure,residual/prediction error, transform coefficient, prediction mode(inter/intra), and intra prediction mode direction, among otherparameters. FAST leverages this information to transfer super resolutiondata from a first frame to a second frame, without application of thesuper resolution process to the second frame.

FIG. 1 is a block diagram 100 illustrating the FAST process. FIG. 2 is aflowchart 200 showing the main steps of FAST. It should be noted thatany process descriptions or blocks in flowcharts should be understood asrepresenting modules, segments, portions of code, or steps that includeone or more instructions for implementing specific logical functions inthe process, and alternative implementations are included within thescope of the present invention in which functions may be executed out oforder from that shown or discussed, including substantially concurrentlyor in reverse order, depending on the functionality involved, as wouldbe understood by those reasonably skilled in the art of the presentinvention.

Compressed video data is received, as shown in block 210. For example,the compressed video data may be a bit stream 110, or the compressedvideo data may be stored in a file. The compressed bit stream 110 isdecoded, for example, with a decoder 120, to produce uncompressed videoframes 130, and syntax elements 135, as shown in block 220. FIG. 1 onlyshows a small subset of possible syntax elements 135 for purposes ofsimplicity. The syntax elements 135 may include, but are not limited tomotion vectors, block structures, residual and/or prediction error,transform coefficients, inter-prediction modes, intra-prediction mode,intra prediction mode directions, skip flags, merge flags, coded blockflags which indicate of residual are all zero, and/or motion vector iszero, loop filter parameters, quantization parameters and/or a referenceindex that indicates a specific reference frame.

The syntax elements generally include information used by the videocompression algorithm to relate objects in successive frames. Forexample, the uncompressed video frames may include an uncompressed firstvideo frame 131, and a uncompressed second video frame 132. The syntaxelements 135 may include, a first frame syntax element, in this case,dimensions (w (width),h (height)) and source position coordinates (x,y)for a first block 165 and a second frame syntax element includingdimensions (w,h) and target position coordinates (x′, y′) for a secondblock 175.

A computationally intensive process 140 is applied to the uncompressedfirst video frame 131 to produce an enhanced first video frame 160, asshown by block 230. For example, the computationally intensive processmay include super resolution upscaling. It should be noted that thecomputationally intensive process 140 may share processing modulesand/or hardware modules/resources with the decoder 120.

An enhanced second video frame 170 is produced without employing thecomputationally intensive process 140. Instead, a block 165 comprising aportion of the enhanced first video frame from the enhanced first videoframe 160 is transferred to the uncompressed second video frame 132 toproduce an enhanced second video frame 170, as shown by block 240. Thetransferring is guided by the syntax elements 135, as will be describedin detail below. The enhanced first video frame 160 and the enhancedsecond video frame 170 may be displayed, for example, with a videodisplay (not shown), as shown by block 250. Alternatively, thecomputationally intensive process 140 may only be applied to a portionof the enhanced second video frame 170, for example, to a subset of oneor more blocks of pixels within the enhanced second video frame 170, asis described herein below.

As described further below, a uncompressed third video frame 133 may beused to produce an enhanced third video frame (not shown) from theenhanced second video frame 160 using the syntax elements 135 in asimilar manner without employing the computationally intensive process140.

It should be noted that the transfer step alone can introduce visualdegradation. FAST addresses this by adaptively enabling and disablingthe transfer via a model that measures the visual quality loss, asdescribed below. To further accelerate the processing, FAST may usenon-overlapping block structure embedded in the compressed 110 video,rather than the overlapping blocks traditionally used for SR. FASTapplies a lightweight blocking filter, for example, a High EfficiencyVideo Coding (HEVC) deblocking filter to remove the resulting blockingartifacts. FAST adapts its processing to the varying video content(e.g., blocks with different sizes, blocks with zero motion vector andzero residuals) for additional acceleration.

The decoder 120 decompresses a compressed video 110 to be α∈Z⁺timeslarger. Here, α is the scale of the up-sampling. For example,up-sampling a video from 1920×1080 (full HD) to 3840×2160 (4K) wouldhave α=2. In practice, a may be set to 2, 3 or 4. However, theoreticallyα may be any positive integer, which forms a set Z⁺, i.e., the set ofpositive integers.

For simplicity, the following explanation only considers two adjacentframes, the uncompressed first video frame 131 and the uncompressedsecond video frame 132, where some blocks in the uncompressed secondvideo frame 132 are predicted by motion compensated blocks in theuncompressed first video frame 131, as indicated by the syntax elements135. The goal is to compute higher resolution images for the enhancedfirst video frame 160 and the enhanced second video frame 170. It isunderstood that the enhanced first video frame 160 and the enhancedsecond video frame 170 have a higher resolution than the uncompressedfirst video frame 131 and the uncompressed second video frame 132. Someblocks in the uncompressed second video frame 132 may not be predictedfrom frame 131, and instead may be intra-predicted, and thus are nottransferred. For such intra predicted blocks in 132, SR may be applied,bicubic processing may be applied, or another low complexity up-samplingapproach may be applied.

The computationally intensive process 140, for example, an SR algorithm,is applied on the uncompressed first video frame 131 to obtain theenhanced first video frame 160. Instead of applying the computationallyintensive process 140 on the uncompressed second video frame 132 to getthe enhanced second video frame 170, temporal correlation withinformation from the syntax elements 135 are exploited to transfer (copywithout additional processing) pixels from the enhanced first videoframe 160 to the enhanced second video frame 170.

The adaptive transfer process 150 transfers pixels from the enhancedfirst video frame 160 to the enhanced second video frame 170 block byblock. For example, the first block 165 and second frame syntax elements135 including the dimensions (w,h) and a target position (x′, y′) may becombined with an up-sampled low-resolution residual for the target blockfrom the uncompressed second video frame 132 to form a higher resolutionblock in the enhanced second video frame, namely the second block 175.The second block 175 incorporates the enhancement of the first block 165as applied to the enhanced second frame 170 via the computationallyintensive process 140, compensating for relative position/motion withinthe enhanced second frame 170 using syntax elements 135 such aspositional information, predicted direction information, motion vectorsand the like. If the position of the second block 175 within theenhanced second frame 170 includes a fractional portion (that is, theposition of the second block 175 within the enhanced second video frame170 does not align on pixel mappings of the enhanced second frame 170),the adaptive transfer process 150 may employ interpolation toapproximate the position.

The adaptive transfer process 150 may skip applying the computationallyintensive process 140 to the second frame entirely, and all operationsin the adaptive transfer process 150 may be of lower complexity than SR,for example, similar in complexity to bicubic up-sampling. This givessignificant savings in computation compared to that of modern SRalgorithms such as SRCNN.

The adaptive transfer process 150 may use intra-prediction for thetransfer of some blocks to the enhanced second video frame 170 wherethere are no super-resolution results to transfer. Typically, this isrelatively infrequent, and relates to blocks containing very simpletextures. Therefore, the adaptive transfer process 150 may up-samplethese blocks using, for example, bicubic up-sampling.

A motion vector in the syntax elements 135 may be pixel accurate orsub-pixel accurate, which has a large impact on the visual quality ofthe enhanced second frame 170.

The adaptive transfer process 150 may be applied using integer pixel,half-pixel and quarter pixel accuracy. The Peak Signal-to-Noise Ratio(PSNR) generally increases with the higher of motion vector accuracy,indicating the desirability of using a quarter-pixel motion vector.Fortunately, motion vectors with quarter pixel accuracy are available inmodern video codecs which is sufficient to enable high quality transfer.The motion vectors, as with all the syntax elements 135, are embedded inthe compressed video, and do not increase the computational load on theadaptive transfer process.

In practice, motion compensation may not be exact. The adaptive transferprocess 150 applies up-sampling to a resulting residual, for example,bicubic up-sampling, which may introduce two types of errors: ringingartifacts in a single frame and accumulated error across multipleframes.

Some blocks 165 may have prediction residual high in energy and maycontain sharp edges, which causes ringing artifacts on the transferredoutput. Such artifacts typically occur on the smooth image regions,rather than at sharp edges. Intuitively, this occurs when the encoderpredicts a smooth region with a source block that contains a sharp edge.Consequently, the prediction residual may also have a sharp edge at thesame position. By running the computationally intensive process 140 onthe source frame 131, the sharp edge is preserved in the enhanced firstframe 160, but the edge on the residual may be blurred in the resultingenhanced second frame 170 due to bicubic interpolation of the adaptivetransfer process 150. The combination of a sharp edge with a blurry edgeunsurprisingly creates ringing artifacts, as shown in FIG. 3.

To avoid the ringing artifacts, the adaptive transfer process 150 maycompute a mean absolute magnitude of the residual block, and compare themean absolute magnitude to a residual threshold η to decide whether ornot to transfer the block, as described further below. If the magnitudeof the residual is below the residual threshold η, a transfer isperformed. Otherwise, the low-resolution block may be directlyup-sampled, for example, using bicubic interpolation.

To properly learn the residual threshold many pairs of source and targetimages may be collected, and synthetically down-sampled to lowerresolution. Then the low-resolution target image is divided into blocks.For each low resolution target block the best prediction block on thesource image is searched for the result that gives the smallestprediction error. Here the mean sum of absolute difference (SAD) is usedas the error metric. e_(i) denotes the resulting prediction error for acorresponding block P_(i). The superscript h stands for high-resolution,t stand for transfer, and b stands for bicubic interpolation. Given thetransferred outputs (P_(i) ^(h;t)) and the up-sampled residual withbicubic interpolation (P_(i) ^(h;b)), the respective PSNR, y_(i) ^(t)and y_(i) ^(b) may be computed. Assuming the adaptive transfer process150 only transfers when e_(i)<η, then the residual threshold η may bechosen to maximize the PSNR across all blocks with the followingoptimization:

$\begin{matrix}{{\max\limits_{\eta}{\sum\limits_{i,{e_{i} \leq \eta}}y_{i}^{i}}} + {\sum\limits_{i,{e_{i} > \eta}}y_{i}^{b}}} & ( {{Eq}.\mspace{14mu} 1} )\end{matrix}$

While thresholding the image content in order to adaptively apply eitherbicubic interpolation or sophisticated super-resolution methods hastypically been used as an acceleration tool, the adaptive transferprocess 150 incorporates thresholding the image content to achievehigher visual quality. This may also be achieved during in-place exampleregression SR by decomposing a block to an in-place prediction and itsresidual. In place example regression SR typically performs worsewithout thresholding. However, proper thresholding providessignificantly higher PSNR.

Up-sampling the residual to the higher resolution using bicubicinterpolation as an approximation introduces errors, as is shown in Eq.(2) and (3). In a chained GOP structure (IPPP), a frame is alwayspredicted by the previous frame; thus the error gets accumulated. Iflarge enough, this error can degrade the visual quality of thetransferred frame, for example, via artifacts such as blurred regions orjagged edges. The described embodiments incorporate a model to quantifythe accumulated error, on which a threshold may be performed to decidewhether the accumulated error is acceptable, or whether instead SRshould be applied to the next frame.

Specifically, let us denote the result of FAST at frame t by P^(h) _(t),(x) as opposed to the SR result P^(h) _(t)(x). Under this notation, aTaylor expansion approximation of SR and FAST rendered frames may bewritten as:P _(t) ^(h)(αx)=f _(ar)(P _(t-1) ¹(x+dx _(t-1→t)))+(∇f _(ar) ,R _(t-1→t)¹(x))P _(t) ^(h1)(ax)=P _(t-1) ^(h1)(α(x+dx _(t-1→t)))+b(R _(t-1→t) ¹(x))  (Eq. 2)

Defining the transfer error as e^(h) _(t)(αx) as the difference betweenthe FAST frame and the SR frame and substituting into Eq. 2 results in

$\begin{matrix}\begin{matrix}{{e_{t}^{h}( {\alpha\; x} )} = {{P_{t}^{h\;\prime}( {\alpha\; x} )} - {P_{t}^{h}( {\alpha\; x} )}}} \\{= {( {{P_{t - 1}^{h\;\prime}( {\alpha\;( {x + {dx}_{{t - 1}arrow t}} )} )} + {b( {R_{{t - 1}arrow t}^{l}(x)} )}} ) -}} \\{( {f_{sr}( {{P_{t - 1}^{l}( {x + {dx}_{{t - 1}arrow t}} )} + \langle {{\nabla f_{sr}},{R_{{t - 1}arrow t}^{l}(x)}} \rangle} )} } \\{= {( {{P_{t - 1}^{h\;\prime}( {\alpha\;( {x + {dx}_{{t - 1}arrow t}} )} )} - {P_{t - 1}^{h}( {\alpha( {x + {dx}_{{t - 1}arrow t}} )} )}} ) +}} \\{( {{b( {R_{{t - 1}arrow t}^{l}(x)} )} - ( {{\nabla f_{sr}},{R_{{t - 1}arrow t}^{l}(x)}} \rangle} )} \\{= ( {{e_{t - 1}^{h\;}( {\alpha\;( {x + {dx}_{{t - 1}arrow t}} )} )} + ( {{b( {R_{{t - 1}arrow t}^{l}(x)} )} -} } } \\ \langle {{\nabla f_{sr}},{R_{{t - 1}arrow t}^{l}(x)}} \rangle )\end{matrix} & ( {{Eq}.\mspace{14mu} 3} )\end{matrix}$

This expression may be reduced toe _(t) ^(l)(x)=e _(t-1) ^(l)(x+dx _(t-1→t))−ΔR _(t-1→t) ^(l)(x)   (Eq.4)

This suggests that the transfer error of a new frame is the motioncompensated transfer error from the previous error plus the Laplacian ofthe residual of the current frame. Therefore, the Laplacian of theresidual gets accumulated. The computation for this error only involvessimple interpolation and addition. For each block, the FAST frameworkmay compute the average absolute magnitude of the accumulated error. Ifaverage absolute magnitude of the accumulated error is above a giventhreshold, for example, the residual thresholdr η described previously,the transfer is stopped and the SR algorithm is applied to itslower-resolution decoded block 132. This resets the accumulated error to0.

FIG. 4 is a flowchart 400 of an exemplary process for applyingaccumulated error analysis to the FAST framework. An enhanced firstvideo frame is produced and displayed from received compressed videodata using SR, and an enhanced second video frame is produced anddisplayed from received compressed video data using the FAST framework,as shown by block 200. It should be noted that an expanded version ofblock 200 is shown by FIG. 2. An initial accumulated error between eachblock of the enhanced video frame and the enhanced second video frame isdetermined, as shown by block 410. An accumulated error threshold value,for example the residual threshold is determined, as shown by block 420.For each block in the enhanced second video frame, the accumulated erroris compared with the accumulated error threshold, as shown by block 430.If the accumulated error is below the error threshold, a correspondingblock in the next enhanced video frame is produced using the FASTframework, as shown by blocks 440 and 450. If the accumulated errormeets or exceeds the error threshold, a corresponding block in the nextenhanced video frame is produced using SR, as shown by blocks 440 and460. As shown by block 470, the block comparison continues for eachblock of the enhanced second video frame.

The content of different blocks within a frame may result in differenttypes of accumulated error. For example, smooth blocks (blocks that donot contain well defined edges) do not introduce accumulated error ingeneral. A non-occluding edge is often well-predicted from the same edgein the previous frame, so the residual magnitude may generally be smallenough to be disregarded whether the block is moving or not. Also, theaccumulated error is not dependent on the low-frequency component of theresidual. So for blocks with changing brightness, the accumulated errormay still be negligible. If a block lies on a moving occluding edge in ahighly textured area, the error may accumulate rapidly due to the newand unpredictable textures that come out of the occlusion.

While the above embodiment uses accumulated error as an exemplary metricfor adaptive transfer, for example, determining when to revert to SRprocessing over FAST, the same methodology may use metrics for adaptivetransfer indicating a quality and/or computation cost change betweensubsequent frames and/or blocks. For example another decision makingmetric involves transfer between neighboring blocks in a frame. If FASTdetermines one block is to be transferred, then it is likely thatneighboring blocks should also be transferred for better spatialconsistency. This spatial relationship between the blocks isquantifiable and may serve as a factor in the metric for making adecision during adaptive transfer.

The rate of error accumulation for FAST depends on the GOP structure.The chained GOP structure (IPPP) yields poor FAST results because theerror is accumulated across frames sequentially. Other GOP structuresresult in better FAST results. For example, in the IBBP GOP structure,the error is only accumulated twice (I→P→B).

Most of the SR algorithms divide an image into densely overlappedblocks, and average the output on these overlapped blocks to avoiddiscontinuities on the block boundaries. This is computationally veryexpensive since one pixel in a frame is processed multiple times indifferent blocks that cover it. While the above embodiments may beimplemented using densely overlapped blocks, the FAST frameworkpreferably uses a non-overlapping block structure used in video coding,so that each pixel is covered by exactly one block. Hence each pixel isonly processed once, which significantly reduces the number ofcomputations. An image may be adaptively divided into non-overlappingblocks, with larger blocks corresponding to simple and well-predictedcontent.

While use of a non-overlapping block structure may introduce artificialedges on the block boundary, FAST addresses this by applying an adaptivedeblocking filter, for example, but not limited to the deblocking filterused in H.265/HEVC. The main objective of the deblocking filter is toremove the artificial edges on the block boundary due to non-overlappingblock based coding while keeping the true edges. An important heuristicis that an edge tends to be artificial if there is little variations onboth sides of the block boundary. Additional information like thedifference of motion vectors can also help to determine whether to applythe deblocking filter on each block edge. The smoothing strength of thedeblocking filter is determined based on the statistics of the pixelsnear the block boundary. The capability of non-overlapping blocks withdeblocking filter is also recognized in video coding where such atechnique achieves comparable visual quality with techniques usingoverlapped blocks. The H.265/HEVC deblocking filter is very lightweight,for example, accounting for on the order of 15-20% of the cycles in thewhole decoder running on an ARM processor, and only 3% of the powerconsumption of a low power H.265/HEVC decoder chip.

The output of FAST on a pixel in the high resolution frame is thecombination of the transferred pixel itself and the bicubicly up-sampledresidual, each of which may involve either motion compensationinterpolation for fractional motion vectors, or bicubic interpolationfor up-sampling.

To reduce computations, FAST may leverage the following two conditionsto avoid unnecessary interpolations for certain blocks. First, forblocks with zero motion vector (pixels in zero motion vector blocks),FAST may directly copy the same pixels from the previous frame to thesubsequent frame without interpolation. Second, for blocks with zeroresidual the bicubic interpolation on the residual can be skipped. Theembodiments may check for both conditions by looking at the syntaxelement for each block. For example, the compressed video contains a bitfor each block called the skip flag, which indicates whether theresidual is all zero or not. FAST can also check the value of the motionvectors to see if motion compensation interpolation needs to be applied.Once a block satisfies either of the conditions, FAST applies thecorresponding short-cut to all the pixels within the block.

TABLE 1 Table 1 summarizes the operations available to FAST fordifferent types of blocks. Block types Inter zero Inter Anchored Intraresidual zero mv Inter SR ✓ algorithm Bicubic ✓ ✓ ✓ upsampling Motion ✓✓ compensationAnchored blocks are the blocks where transfer is skipped and SR isapplied. Intra means intra-predicted blocks. Inter refers tointer-predicted blocks. Motion vector is abbreviated into my. A checkmark indicates that the operation is indicated by FAST for thecorresponding blocks. For frames with more blocks satisfying either ofthe two conditions above, the more computation reduction FAST can enjoy.In practice, these two conditions are not uncommon, and may be met bymany blocks from compressed videos. Overall, these two conditions mayfurther reduce the computation cost of FAST by more than half than whenthese conditions are not considered.

As noted above, in H.264/AVC and H.265/HEVC, frames may be divided intoblocks of varying size, with larger blocks assigned to flat orwell-predictable regions and smaller blocks assigned to highly texturedareas. FAST may gain additional efficiencies by copying and skipping thepixels that belong to large blocks with a single check on residualskip-flag and zero motion vector. It has been observed that often asignificant portion of pixels that are copied or skipped, rather thanprocessed, belong to largest blocks.

The present system for executing the functionality described in detailabove may be a computer, an example of which is shown in the schematicdiagram of FIG. 5. The system 500 contains a processor 502, a storagedevice 504, a memory 506 having software 508 stored therein that definesthe abovementioned functionality, input and output (I/O) devices 510 (orperipherals), and a local bus, or local interface 512 allowing forcommunication within the system 500. The local interface 512 can be, forexample but not limited to, one or more buses or other wired or wirelessconnections, as is known in the art. The local interface 512 may haveadditional elements, which are omitted for simplicity, such ascontrollers, buffers (caches), drivers, repeaters, and receivers, toenable communications. Further, the local interface 512 may includeaddress, control, and/or data connections to enable appropriatecommunications among the aforementioned components.

The processor 502 is a hardware device for executing software,particularly that stored in the memory 506. The processor 502 can be anycustom made or commercially available single core or multi-coreprocessor, a central processing unit (CPU), an auxiliary processor amongseveral processors associated with the present system 500, asemiconductor based microprocessor (in the form of a microchip or chipset), a macroprocessor, or generally any device for executing softwareinstructions.

The memory 506 can include any one or combination of volatile memoryelements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM,etc.)) and nonvolatile memory elements (e.g., ROM, hard drive, tape,CDROM, etc.). Moreover, the memory 506 may incorporate electronic,magnetic, optical, and/or other types of storage media. Note that thememory 506 can have a distributed architecture, where various componentsare situated remotely from one another, but can be accessed by theprocessor 502.

The software 508 defines functionality performed by the system 500, inaccordance with the present invention. The software 508 in the memory506 may include one or more separate programs, each of which contains anordered listing of executable instructions for implementing logicalfunctions of the system 500, as described below. The memory 506 maycontain an operating system (O/S) 520. The operating system essentiallycontrols the execution of programs within the system 500 and providesscheduling, input-output control, file and data management, memorymanagement, and communication control and related services.

The I/O devices 510 may include input devices, for example but notlimited to, a keyboard, mouse, scanner, microphone, etc. Furthermore,the I/O devices 510 may also include output devices, for example but notlimited to, a printer, display, etc. Finally, the I/O devices 510 mayfurther include devices that communicate via both inputs and outputs,for instance but not limited to, a modulator/demodulator (modem; foraccessing another device, system, or network), a radio frequency (RF) orother transceiver, a telephonic interface, a bridge, a router, or otherdevice.

When the system 500 is in operation, the processor 502 is configured toexecute the software 508 stored within the memory 506, to communicatedata to and from the memory 506, and to generally control operations ofthe system 500 pursuant to the software 508, as explained above.

When the functionality of the system 500 is in operation, the processor502 is configured to execute the software 508 stored within the memory506, to communicate data to and from the memory 506, and to generallycontrol operations of the system 500 pursuant to the software 508. Theoperating system 520 is read by the processor 502, perhaps bufferedwithin the processor 502, and then executed.

When the system 500 is implemented in software 508, it should be notedthat instructions for implementing the system 500 can be stored on anycomputer-readable medium for use by or in connection with anycomputer-related device, system, or method. Such a computer-readablemedium may, in some embodiments, correspond to either or both the memory506 or the storage device 504. In the context of this document, acomputer-readable medium is an electronic, magnetic, optical, or otherphysical device or means that can contain or store a computer programfor use by or in connection with a computer-related device, system, ormethod. Instructions for implementing the system can be embodied in anycomputer-readable medium for use by or in connection with the processoror other such instruction execution system, apparatus, or device.Although the processor 502 has been mentioned by way of example, suchinstruction execution system, apparatus, or device may, in someembodiments, be any computer-based system, processor-containing system,or other system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions. Inthe context of this document, a “computer-readable medium” can be anymeans that can store, communicate, propagate, or transport the programfor use by or in connection with the processor or other such instructionexecution system, apparatus, or device.

Such a computer-readable medium can be, for example but not limited to,an electronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or propagation medium. Morespecific examples (a nonexhaustive list) of the computer-readable mediumwould include the following: an electrical connection (electronic)having one or more wires, a portable computer diskette (magnetic), arandom access memory (RAM) (electronic), a read-only memory (ROM)(electronic), an erasable programmable read-only memory (EPROM, EEPROM,or Flash memory) (electronic), an optical fiber (optical), and aportable compact disc read-only memory (CDROM) (optical). Note that thecomputer-readable medium could even be paper or another suitable mediumupon which the program is printed, as the program can be electronicallycaptured, via for instance optical scanning of the paper or othermedium, then compiled, interpreted or otherwise processed in a suitablemanner if necessary, and then stored in a computer memory.

In an alternative embodiment, where the system 500 is implemented inhardware, the system 500 can be implemented with any or a combination ofthe following technologies, which are each well known in the art: adiscrete logic circuit(s) having logic gates for implementing logicfunctions upon data signals, an application specific integrated circuit(ASIC) having appropriate combinational logic gates, a programmable gatearray(s) (PGA), a field programmable gate array (FPGA), etc.

In addition to the benefits of the embodiments described above, use ofFAST embodiments may avoid flickering introduced by individual framebased video enhancement. Running video enhancement algorithm such as SRframe by frame may ignore the temporal correlation between the sameobject in two adjacent frames. Even if the object just moves slightly,the video enhancement algorithm may enhance its appearances in twodifferent frames differently, causing the flickering. FAST avoids thiseffect by exploiting the motion vectors and the residue in thecompressed video frame, which captures the temporal correlation.Therefore, the enhanced frame of FAST embodiments depends on theenhanced result of previous frame, which enforces the temporalconsistency and avoids the flickering.

In summary, embodiments described above exploit information embedded incompressed video that previously had not been used for super-resolutionalgorithms, including prediction residuals, and varying block sizes.These embodiments may incorporate non-overlapping blocks and deblockingfilters for super-resolution, and take advantage of the fact that manyblocks of pixels in typical video sequences have either zero motionvectors or zero prediction residuals. Thus, in addition to reducing SRprocessing, this avoids unnecessary bicubic interpolation.

Since the embodiments described above consume significantly less time,processor, and power resources as full SR processing, the embodimentsmay be incorporated into platforms where full SR processing maypreviously have been impractical, for example, in smart phones, tablets,televisions, computers, and other consumer, commercial, and industrialvideo display devices that presently handle and process compressedvideo. Therefore, the exemplary methods directly improve thefunctionality of the video processing of devices and systems executingthe methods by providing higher video resolution using less processingand power. Additional improvements may include, for example, lower heatproduction and greater energy efficiency. Further, the reduction inprocessing requirements may provide some systems to provide real-time SRcapabilities to systems without processing capacity to provideframe-by-frame SR processing.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A method for displaying video on a display by areal-time video processing device comprising a processor and a memorycontaining non-transient instructions that, when executed by theprocessor, comprise the steps of: receiving compressed video data;decoding the compressed video data to produce an uncompressed firstvideo frame, a first frame syntax element, an uncompressed second videoframe adjacent to the first video frame in a video sequence, and asecond frame syntax element; applying a first video enhancement processto the uncompressed first video frame to produce an enhanced first videoframe having a higher resolution than the uncompressed first videoframe; applying an adaptive deblocking filter to the enhanced firstvideo frame; applying a second process to the uncompressed second videoframe to produce an enhanced second video frame, further comprising thesteps of: adaptively transferring a block comprising a portion of theenhanced first video frame from the enhanced first video frame to theuncompressed second video frame according to the first frame syntaxelement and the second frame syntax element to produce the enhancedsecond video frame having a higher resolution than the uncompressedsecond video frame; and displaying the enhanced first video frame andthe enhanced second video frame with the display; accumulating a metricfor a parameter indicating a computation cost change and/or a qualitychange between the enhanced first video frame and the enhanced secondvideo frame; determining an accumulated metric threshold value; andcomparing the accumulated metric to the accumulated metric threshold,wherein the first video enhancement process is more computationallyintensive than the second video enhancement process, and the secondvideo enhancement process leverages an inter-frame similarity betweenadjacent frames in the video sequence and transfers an enhancementresult from the first enhanced video frame to the second enhanced videoframe.
 2. The method of claim 1 wherein the first frame syntax elementfurther comprises a size of the block and a source position of theblock, and the second frame syntax element further comprises the size ofthe block, and a target position of the block.
 3. The method of claim 1,wherein the compressed video data comprises a compressed video bitstream.
 4. The method of claim 2, further comprising the step ofdetermining a spatial relationship between pixels in the uncompressedfirst video frame and pixels in the uncompressed second video framebased upon the first frame syntax element and/or the second frame syntaxelement.
 5. A method of claim 4, further comprising the step of avoidingprocessing to speed up a rendering of the enhanced second video framebased at least in part on the spatial relationship between pixels in theuncompressed first video frame and pixels in the uncompressed secondvideo frame.
 6. The method of claim 4, further comprising the step ofcombining a first pixel from the uncompressed first video frame with arelated second pixel from the uncompressed second video frame forimproving an image quality in the enhanced second video frame.
 7. Themethod of claim 6, wherein the improving the image quality in theenhanced second video frame comprises super resolution enhancement,dynamic range expansion, object recognition and/or detection, opticalflow estimation, time-to-contact estimation, tracking in videos, videostabilization, video segmentation, frame interpolation, sceneunderstanding, visual style editing, deblurring, high dynamic rangeenhancement, and reducing a level of noise in the enhanced second videoframe.
 8. A method of claim 1, wherein the first frame syntax elementand/or the second frame syntax element comprises one or more of thegroup consisting of a motion vector, a block structure, a residualand/or prediction error, a transform coefficient, an inter predictionmode, an intra prediction mode, an intra prediction mode direction, askip flag, a merge flag, a coded block flag, a loop filter parameter, aquantization parameter, and a reference index.
 9. The method of claim 1,further comprising the steps of: decompressing the compressed video datato produce an uncompressed third video frame, and a third frame syntaxelement; and transferring a block comprising a portion of the enhancedsecond video frame from the enhanced second video frame to theuncompressed third video frame according to the frame syntax element andthe third frame syntax element to produce an enhanced third video framehaving a higher resolution than the uncompressed third video framewithout applying the first video enhancement process to the uncompressedthird video frame.
 10. The method of claim 9, wherein the third framesyntax element further comprises the size of the block, and a secondtarget position of the block.
 11. The method of clam 1, furthercomprising the steps of: for an enhanced first video frame and anenhanced second video frame where the accumulated metric is below theaccumulated metric threshold value, adaptively transferring a blockcomprising a portion of the enhanced second video frame from theenhanced second video frame to a uncompressed third video frame toproduce an enhanced third video frame without applying the first videoenhancement process to the uncompressed third video frame, for anenhanced frame an enhanced second video frame where the accumulatedmetric meets or exceeds the accumulated metric threshold value,producing an enhanced third video frame using the computationallyintensive process.
 12. The method of claim 1, wherein applying the firstvideo enhancement process to the uncompressed first video frame toproduce the enhanced first video frame further comprises dividing theenhanced first video frame into a plurality of non-overlapping blocks sothat each pixel is included by exactly one block of the plurality ofnon-overlapping blocks.
 13. The method of claim 12, wherein a firstblock of the plurality of non-overlapping blocks comprises a largernumber of pixels than a second block of the plurality of non-overlappingblocks, wherein the pixels of the first block correspond to a simplerstructure and/or better-predicted content than the pixels of the secondblock.
 14. The method of claim 1, further comprising the step of forblocks with zero motion vector and/or zero residual, directly copyingthe same pixels from the enhanced first video frame to the uncompressedsecond video frame without interpolation.
 15. The method of claim 1,wherein the accumulated metric comprises an indication of accumulatederror, and the accumulated metric threshold comprises an accumulatederror threshold.
 16. A real-time video display system comprising: adecoder comprising a first processor and a first memory containingnon-transient instructions that, when executed by the first processor,comprise the steps of: receiving compressed video data; and decoding thecompressed video data to produce an uncompressed first video frame, afirst frame syntax element, an uncompressed second video frame adjacentto the first video frame in a video sequence, uncompressed second videoframe, and a second frame syntax element; a video processing device incommunication with the decoder comprising a second processor and asecond memory containing non-transient instructions that, when executedby the second processor, comprise the steps of: applying a first videoenhancement process to the first uncompressed video frame to produce anenhanced first video frame having a higher resolution than theuncompressed first video frame; and applying a second process to theuncompressed second video frame to produce an enhanced second video,further comprising the steps of: adaptively transferring a blockcomprising a portion of the enhanced first video frame from the enhancedfirst video frame to the uncompressed second video frame according tofirst frame syntax element and the second frame syntax element toproduce the enhanced second video frame having a higher resolution thanthe uncompressed second video frame, wherein the first video enhancementprocess is more computationally intensive than the second videoenhancement process, and the second video enhancement process leveragesan inter-frame similarity between adjacent frames in the video sequenceand transfers an enhancement result from the first enhanced video frameto the second enhanced video frame; and a video display configured todisplay the enhanced first video flame and the enhanced second videoframe with the display.
 17. The system of claim 16, wherein the videoprocessing device is configured to access a processing module of thedecoder.
 18. The system of claim 17, wherein the processing module isconfigured to execute a functionality of one of the group consisting ofsuper resolution processing, deblocking processing, and motioncompensation processing.
 19. The system of claim 16, further comprisinga decoder memory buffer, wherein the video processing device isconfigured to access the decoder memory buffer.